Adds ability to assert lease & embargo info including visibility_during and visibility_after
refs curationexperts/absolute#34
 * adds embargo/lease history and deactivation date
 * indexes lease_expiration_date when it is set
 * adds lease_active?
 * (minor) cleaning up deprecation warnings
 * adds embargo and lease services
Merge pull request #184 from projecthydra/lease_embargo

Adds ability to assert lease & embargo info including visibility_during ...